Merge pull request #4783 from jtratner/wrap-compressed-fileobjects-in-py3

BUG: Fix input bytes conversion in Py3 to return str
BUG: Fix copy s.t. it always copies index/columns.

Only copies index/columns with `deep=True` on `BlockManager`. Plus some
tests...yay!
Change copy to make views of indices.

Requires changing groupby to check whether indices are identical, rather
than comparing with `is`. Plus add tests for name checks through
everything.